


like a girl in uniform

by WattStalf



Series: it's just piss [89]
Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: F/M, Omorashi, Uniform Kink, Vaginal Sex, Watersports, commission
Language: English
Status: Completed
Published: 2020-03-04
Updated: 2020-03-04
Packaged: 2021-03-01 01:07:06
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,014
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23016736
Author URL: https://archiveofourown.org/users/WattStalf/pseuds/WattStalf
Summary: After Petra accidentally wets herself in front of Byleth, their relationship takes off, until it isn't accidental anymore.
Relationships: Petra Macneary/My Unit | Byleth
Series: it's just piss [89]
Series URL: https://archiveofourown.org/series/397558
Kudos: 16





	like a girl in uniform

Petra is not used to letting things like this get the better of her. Up until now, she has never been in a situation like this, or at least not since she was very young. No, the more she thinks on it, she comes to the conclusion that this did not happen when she was young either. In Brigid, at home, things were different, and she was different, and even as a child, there was no shame in the way she did things, because that was how everyone did things.

It isn’t like that in Fodlan, and she hasn’t had a problem with that before now. Before now, she has always hunted by herself, though. Today, she has a guest with her, and that guest is someone that she only ever wants to see her in a good light. That, combined with how tongue tied this language still makes her even after living here for as long as she has, makes it difficult for her to address the issue at hand.

Which is to say, Petra has to pee, and she doesn’t want to tell Byleth about it.

The two have gotten a lot closer lately, and she knows that there is something special building between the two of them, which is why she has spent the better part of today hunting with him. But she hasn’t been able to relieve herself outside like she would if she were alone, and she is absolutely bursting now, stiff and hardly able to contain herself as they make their way back to the monastery.

“Are you okay?” asks Byleth, noticing her discomfort, making her blush.

“I am fine! I am just…” She wishes that she could just admit to the problem and duck behind a tree; she’s going to lose it any minute now, she just knows it. “I am just needing to get back quickly.”

“Why is that?” asks Byleth. “We can hurry, if you need to.”

“That’s...I am…” She struggles with the words, squeezing her thighs together, blushing harder when she notices Byleth’s eyes dropping down. He must already know, even before she speaks, because he does not seem surprised when she says, “I am needing to relieve myself.”

“We can hurry,” he repeats, but there is something off about his voice, and something in the way his eyes linger on her as he speaks. He takes her hand as if it is the most natural thing in the world, guiding her back through the forest, but it’s no use. Already, her bladder is so full that each step pains her. She’s needed this for hours now, put it off for far too long.

No matter how Byleth tries to hurry her along, she has no choice. She humiliates herself in front of him as she slows to a stop, pulling her hand from his to push it between her legs with the other hand, doubling over and whimpering as the floodgates let loose. Byleth watches her, that strange look in his eyes, as she soaks her outfit, as the stream runs down her legs, as she completely pisses herself.

This should be the end of everything between the two of them, but it isn’t. It serves instead as the push they need, as a beginning. At first, Petra doesn’t understand what Byleth tries to say to her, but in the end, she understands perfectly.

~X~

Later, once they have settled into their relationship and once she has come to understand Byleth’s interest in her accident, Petra is happy to play along with whatever indulgences may interest her lover at the moment. Today it is her uniform, from back when she was still just a student at the academy, an outfit that she has long since abandoned for more traditional Brigid clothing.

He wants to see her squirm in it, and she wears it for him, despite how much she has grown since then. It hardly fits her now, snug all over and so short now that it leaves the entirety of her long legs exposed, and even more beyond that. Her shirt is tight along her chest, and her skirt, in addition to being too short, is tight along her hips, leaving nothing to the imagination. Byleth must have known this would be the outcome, never failing to surprise her with how secretly lecherous he can be. That’s fine; Petra has come to find that she very much likes that side of him.

The tightness does cause a bit of a problem for her, in the discomfort that it adds to her already full bladder. Her skirt cuts across her midsection, digging into her and adding more pressure when she is under enough pressure already. She has made sure to drink plenty, so that he will definitely get to see her squirm. Petra will only be allowed to go if Byleth lets her, and she has a feeling that that is definitely not happening tonight.

He waits for her, giving her a long once over when she enters the room and closes the door behind her. Already, she feels like she is going to burst. She doesn’t know how she is going to make it through this, or even how long she is going to make it. It hurts so much, and he can tell in the way that she moves, squirming from side to side, already unable to stand still.

“You’ve done such a good job,” he praises her, and that makes her smile. As painful as holding it in is, she likes to do it because Byleth likes it, and she has come to appreciate it quite a bit on her own. He doesn’t smile for anyone else in quite the same way that he does for her, and it’s nice to be able to earn such big reactions out of the typically stoic professor.

“Do I look good?” she asks, pleased with herself for not getting her words mixed up. She wants to show off her outfit, but she soon finds her legs snapping together, a hand nervously tugging on her short skirt.

“You look amazing,” Byleth breathes, and it is evident in the way that he can’t stop staring at her, the way his eyes travel up and down her shaky legs. He must be able to tell just how badly she has to pee right now, and is eager to see what will happen as she continues to push that limit.

Of course, he is rarely able to wait for her to lose control before he is already giving into his own desires, having his way with her before the dam bursts, then enjoying the way it all flows out over the two of them. It is pure ecstasy for both of them; for Byleth, as he enjoys one of his favorite indulgences, and for Petra, as she is finally able to have relief, after forcing herself to hold back so much for him.

As it is right now, she is absolute bursting, trembling as she tries to pose for him, showing off her uniform as best as she can without causing herself to prematurely lose control. She is so desperate that she knows she will not last much longer, but as she jams a hand between her leg, causing her short skirt to push up even further, she does not think that Byleth will be able to last  _ that _ long.

Her skirt is so short that if she were not wearing panties, he would be able to see everything right now. Since she is wearing panties, something that Byleth always insists on, he can just see those, and can see the slight damp spot left on them. Even she isn’t sure if that is just evidence of her arousal showing, or if she may have leaked a little bit without noticing. Either way, Byleth stares at that spot in particular, and Petra blushes a bit, ashamed despite knowing that he likes it.

She pushes her hand deeper between her legs, squirming and rubbing her thighs together, groaning and whimpering and putting on a show of trying to hold it for him, but nothing that she does is enough to alleviate the pressure. Petra is at her very limit, already on the verge of wetting herself, and Byleth can tell. If he is just patient for a moment longer, then he will get to watch her panties grow darker and darker, until streams of urine are running down both of her long legs.

But Byleth is not patient, and before she has the chance to register it, he is upon her, pulling her close and pulling her on top of him, laying back so that she can straddle him. His cock is already freed, and in the commotion, she loses it a little bit before she is able to regain control, dampening her panties even more as a result. Byleth reaches up to pull her panties to the side, just enough to grant him entrance, and then pulls her down onto him, his cock pushing up into her.

Petra cries out as he groans, the two of them losing themselves in the pleasure of it immediately. Byleth is breathless and needy as he buries himself in her, and Petra sinks down onto him, her pleasure growing so much that she can nearly ignore her bladder aching for relief, stretched beyond its limits, sore and ready to burst. And as he begins to thrust up into her, jostling her on top of him as he fucks her, there is no way that she can hope to contain that.

With a cry that is both surprised and ecstatic, she loses control while Byleth fucks her, her bladder no longer able to hold back the flood. Petra pisses herself right on top of him, while he is buried inside of her, the contents of her bladder gushing out with torrential force, soaking the man beneath her as he groans and drives up into her, quickly overcome and reduced to needy moans and reckless, uncontrolled thrusts.

Watching her lose control and feeling her hot piss soak him are both too much for Byleth to handle, and he is soon fucking her with abandon. And Petra is so overwhelmed by the relief of finally emptying her aching bladder, still a little sore from holding back so much, that this only serves to increase her pleasure, until she is bouncing along with each thrust, riding him as she gives in to her ecstasy.

It is not long before she is so lost in it that her climax surprises her, coming on suddenly and reducing her to an incoherent mess, crying out for Byleth in a mixture of words, his language and her language mingling together as she is left unaware of everything that she says, barely aware of where or who she is anymore. She has never felt so amazing before Byleth showed her just how amazing she  _ could _ feel.

As for him, he was already near his limit just to feel her wet herself on him, and now he has no hope left of holding back. It only takes a few more weak thrusts up into her before he is giving in as well, letting his ecstasy wash over him as he jerks his hips one last time, his delight spilling over as he comes up into her, moaning her name, hardly any more coherent than she is.

After that, the two of them are left to catch their breath, both wet and sticky with the mixture of fluids, as Petra slumps over on top of him. Byleth holds her close while she catches her breath, and her first coherent thought is about how glad she is that her old uniform already doesn’t fit her well anymore. It will probably take a lot of effort to get it clean after that, and she is glad that she will not have to worry about wearing it for anyone else but Byleth.

Of course, she’s sure that he doesn’t mind the mess either way.

**Author's Note:**

> If you're interested in my writing updates, please follow my fanfiction twitter @WattStalf  
> 


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